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ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells
N R Jorgensen1, S T Geist, R Civitelli
1Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
The Journal of Cell Biology
|October 23, 1997
Summary
Cell communication relies on calcium waves. This study reveals ATP-dependent pathways and a novel connexin43 mechanism for calcium wave propagation, distinct from inositol trisphosphate signaling.
Area of Science:
- Cell Biology
- Biophysics
- Physiology
Background:
- Cells coordinate activities via intercellular calcium waves.
- Two models exist for nonexcitable cells: inositol trisphosphate (IP3) transfer through gap junctions or ATP acting on P2 purinergic receptors.
Purpose of the Study:
- To investigate mechanically induced calcium waves in rat osteosarcoma cell lines with differing gap junction proteins and purinergic receptor expression.
- To elucidate the mechanisms of intercellular calcium wave propagation.
Main Methods:
- Studied mechanically induced calcium waves in ROS 17/2.8 (Cx43, no P2U) and UMR 106-01 (Cx45, P2U) rat osteosarcoma cell lines.
- Utilized transfectants (ROS/P2U, UMR/Cx43) and hamster tracheal epithelia cells.
- Assessed dye coupling and calcium store release.
Main Results:
- ROS 17/2.8 cells showed slow, gap junction-dependent waves (Cx43) without calcium store release.
- UMR 106-01 cells exhibited fast, P2U receptor-dependent waves requiring calcium store release, independent of gap junctions.
- Transfectants and epithelial cells displayed both wave types, confirming ATP-dependent and novel Cx43-dependent pathways.
Conclusions:
- P2U purinergic receptor activation propagates intercellular calcium waves.
- A novel Cx43-dependent mechanism for calcium wave propagation exists, independent of IP3-mediated calcium store release.
- Gap junction communication via Cx43 or Cx45 poorly facilitates IP3 passage for calcium store release.